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Khmer Rouge cryptographer explains regime’s codes

Khmer Rouge leaders and cadres were so paranoid about messages being intercepted that communications took place on special frequencies and secret signals were exchanged between the sender and receiver before transmission could occur, said Norng Sophang, a former telegraph and code operator who testified at the Khmer Rouge tribunal yesterday.

Sophang, a 60-year-old retired teacher, spent much of his day on the stand delving into the nitty gritty of the intricate system.

In response to questions posed by senior assistant to the international co-prosecutor Tarik Abdulhak, he told the court that senior leaders would send transmissions to the zones using a special technique, and that telegrams were given an extra wrinkle of encryption depending on the level of classification.

A recipient trying to decipher some of the most sensitive documents, for example, would have to work through a few steps.

“There are three layers for the process of encryption in order to make the message final,” Sophang said. “The most confidential messages were in relation to the journeys made by the cadres … and secondly, it was the internal affairs, that is, what happened in various bases, that would fall under this category as well.”

At his job, Sophang taught others how to use and understand one of the more basic methods, which involved a 100-cell table filled with letters and numbers.

To unlock the numerical part of a telegram using the table, the reader would have to know that each character in the table translates corresponding figures in the rows and columns.

“For instance, for number nine, that is number 1 [on the vertical column], and on the horizontal line it is number 8, so 18 represents number nine.”

Numbers, Sophang added, could describe offices and even people. Son Sen, Democratic Kampuchea’s defence minister, was referred to simply as 47.

“And in relation to an open message, as in unencrypted, there were very, very few,” Sophang said.

Coding and ambiguous language was another part of the cloak-and-dagger nature of the Khmer Rouge, said Youk Chhang, head of the Documentation Center of Cambodia, which has collected thousands of telegrams from the regime.

Seemingly straightforward telegrams are marked by idiomatic phrasing and a lack of clear reference.

One of their strangest qualities, though, is a heavy reliance on adjectives and adverbs: “felicitously welcome the second anniversary of national independence”; “the super-fantastic 17th of April”; and “let’s congratulate super-excellently the glorious Communist Party of Kampuchea”.

The act of concealment was central to the operation and thinking of Democratic Kampuchea, Youk said. “The Khmer Rouge had a slogan: ‘Secrecy is the key to victory. High secrecy, long survival.’”

To contact the reporter on this story: Joseph Freeman at



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